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 A089708 a(1) = 1, a(2) = 2, a(n) = a(n-1) + d where d is the sum of the absolute differences between all pairs of previous terms. 0
 1, 2, 3, 7, 26, 136, 887, 6785, 59116, 576528, 6215729, 73368729, 940718528, 13016462714, 193285275705, 3065510539375, 51713071208774, 924496937994286, 17458742846249615, 347270877144570683, 7256791451501057782 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n) = a(n-1) + sum_{1<=i=5. Conjecture: a(n) = c n! (1+2/n+(5/2)/n^2+(31/6)/n^3+(317/24)/n^4+O(1/n^5)), where c is about 0.1289432494744. - Dean Hickerson, Nov 15 2003 In closed form, c = BesselJ[3,2] = 0.128943249474402051... - Vaclav Kotesovec, Nov 19 2012 EXAMPLE 26 follows 7 as the sum of the differences of previous terms is (2-1) + (3-1) + (7-1) + (3-2) + (7-2) + (7-3) = 19 and 7+19 = 26. MATHEMATICA a[1]=1; a[2]=2; a[3]=3; a[4]=7; a[n_] := a[n]=(n+1)(a[n-1]-a[n-2])+a[n-3] CROSSREFS Sequence in context: A342155 A308114 A092983 * A107881 A128001 A264829 Adjacent sequences:  A089705 A089706 A089707 * A089709 A089710 A089711 KEYWORD nonn AUTHOR Amarnath Murthy, Nov 14 2003 EXTENSIONS Edited by Dean Hickerson and Ray Chandler, Nov 15 2003 STATUS approved

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Last modified September 19 08:05 EDT 2021. Contains 347556 sequences. (Running on oeis4.)